Mineralogy and Geology. A439 
of flint; they are highly tilted and much flexed. They are unlike any 
of the tertiary series that I have seen in the state, and I am inclined to 
refer them to the lower Silurian age. ) 
ore appears to be mingled with the strata of this formation ina 
series of beds and interlaminations. 
The mine and works are now under the management and general 
superintendence of Capt. H. W. Halleck, formerly of the U. 8. Engi- 
neer Corps. An adit level bas been run in for 900 feet, cutting the old 
workings about 200 feet below the former entrance to the mine; this 
adit is 10 feet by 10, and is well timbered. A railroad of 4 feet guage 
has been laid down throughout its length, and all the ore and refuse 
rock of the mine is brought out in cars that are weighed as they pass 
the office of the mine, and pass to the dressing floors, or to the attle 
heap. ‘The irregularities and contorted windings of the excavations of 
the mine can scarcely be imagined ; they extend in all directions. The 
transit between the upper and lower workings is effected by means of 
stairs or rude steps cut in the slopes, often replaced by notched poles 
instead of ladders. ‘The ore has been followed and excavated wherev- 
er it could be found, and occasional pillars are left to support the roof. 
The prevailing opinion among the miners and others appears to be 
that there is no regular vein of the ore—that it is a “ pocket,” a ‘de- 
posit,” &c. ‘ 
The great width and number of the beds has confounded all ideas of 
extension or prolongation in any particular direction, and led to the 
general belief that the bed is “as broad as it is long,” and the mode of 
working conforms to this view. ‘The character of the deposit may not 
be that of a crue vein, but that it has a determinate extension and di- 
rection I have not the slightest doubt, and I had. abundant evidence of 
the fact. There is no reason why systematic mining should not be 
practised, both on the score of economy and safety. 
The ore is divided into lenticular masses by intercalations of rock of 
variable thickness, and these are often filled with seams and veins of 
the sulphuret. 
N 
lines cavities in the masses of cinnabaf, and is then finely crystallized, 
and sometimes contains small quantities of bitumen in cavities, and im- 
planted in globules among the crystals. 
Sulphurets of iron and copper and arsenical pyrites are associates of 
the ore, but occur in very small quantity. Gol is said to have been 
found frequently in small quantities. 1 searched for crystals of cinna- 
bar in vain, it is all massive, but presents various shades of color, and 
fresh fractures possess great brilliancy and beauty. 
The mine is so free from water that the vein is scarcely decomposed 
atany point. If this had been the case, there would probably be so 
interesting mercurial salts formed along the walls. 
The mining is principally performed by Mexicans and by Yaqui 
ians. ese are eG 
_ ® Similar rocks (talcose and argillaceous shales and a Jasper rock) occur north of 
the harbor Francisco; they are more or less metamorphic, and probably not 
iz Oe ee tee! aie Fa vig) 9 
older than stated above by Mr. Blake—s. v. >. 
enh eM oN a SE 
